A number of patents disclose certain N-aryl-N-(1-substituted-4-piperidinyl)amides having analgesic activity. For example, U.S. Pat. Nos. 3,998,834, 3,164,600, and 4,167,574, issued to Janssen et al. and assigned to Janssen Pharmaceuticals N.V., disclose certain N-phenyl-N-[1-(aryl -substituted)-4-piperidinyl]amide compounds, N-aryl-N-[1-(arylalkyl)-4-piperidinyl] amides and N-aryl-N-[1-(tetrazolyl-substituted)-4-piperidinyl]amides useful as analgesics. U.S. Pat. No. 4,584,303, issued to Huang et al. and assigned to The BOC Group, Inc., discloses certain N-phenyl-N-[1-(heterocyclic)-4-piperidinyl]amide compounds useful as analgesics.
U.S. Pat. No. 4,138,492, issued to Noverola et al. and assigned to Anphar, S. A., discloses certain N-[4'(1'-arylalkyl)piperidinyl]-4-amiino-5-halo-2-alkoxy benzamide compounds. Van Daele et al., Drug Development Research, 8, 225-232 (1986), discloses the preparation of certain 3-hydroxy-4,4-dimethoxy-1-phenylmethyl piperidine derivatives.